Feeding mannan oligosaccharides can fine-tune your pigs’ immune systems, suggests University of Illinois research.

MOS is a product made from the cell wall of yeast. Previous research showed that it increased the growth rate in newly weaned pigs and changed the microbial populations of the digestive tract.

“When it comes to keeping pigs healthy, there are some potentially powerful tools we can use in the diet besides antibiotics,” says James Pettigrew, University of Illinois swine nutritionist. “We have a tendency to think that we can administer health through a needle, by giving pigs antibiotics, and even through systems like all-in/all-out pig flow. These are important, but there also are many health benefits that we can realize through the diet.”

Tung Che, a postdoctoral research associate, led two studies looking at MOS and its effect on pigs experimentally infected with porcine reproductive and respiratory syndrome virus. The studies evaluated how feeding MOS can modulate immune responses in pigs infected with PRRS.

The researchers found MOS can enhance the pigs’ immune responses as well as alleviate overstimulation of the immune system. MOS increases the total number of immune cells such as leukocytes and lymphocytes in the blood in the early infection stage. This could be a significant benefit for producers fighting PRRS.

“This is important because the increase in leukocytes and lymphocytes can help the animal fight not only PRRS but also secondary bacterial co-infections that are common with PRRS,” Che notes. 

Seven days after the study’s PRRS virus inoculation, pigs fed MOS experienced a reduction of fever and had better feed efficiency, indicating a reduction of ongoing inflammation.

“MOS stimulates the immune system and enhances the immune response, except when the immune system is already challenged,” Pettigrew explains. “MOS actually reduces the inflammatory response in pigs with challenged immune systems. This may be how the product improves growth performance because it redirects nutrients to growth rather than to the immune system.”

Che points out that MOS also improved feed efficiency from day 7 to 14 after the animal was inoculated with the PRRS virus.

“PRRS interferes with the immune response and makes pigs more susceptible to bacterial infections,” Pettigrew adds. “MOS seems to counteract this effect.”

Researchers included Pettigrew, Che, Rod Johnson and Keith Kelley from the University of Illinois, Bill Van Alstine of the Animal Disease and Diagnostic Laboratory at Purdue University, and Karl Dawson and Colm Moran of Alltech.